02A boxes are much longer lived than than 020 boxes, seen diesel passats on meay00,000 with orginal box and no issues.
resason you see them getting rebuilt is as there tougher they get put in higher power cars that are haveing more spent on them so why not overhaul it to make sure and make a few adjustments,
they still spit diff rivets out like 020 boxes but not as keenly so diffs get bolted or replaced with lsd and quite often 2nd gear gets a tweek so it'll do 60 in 2nd